Particle measuring device for granule processing apparatus and particle measuring method

ABSTRACT

In a particle measurement device 1 for a powder or granular material processing apparatus, powder or granular material is introduced into a drawing tube 3, which is formed to be projected from the inside of the granulating vessel 2, by injecting high pressure gas from the inside of the granulating vessel 2, so as to capture it with adhesive film 6. The captured powder or granular material is photographed, and, based on the obtained image information, information on the powder or granular material within the granulating vessel 2 is obtained. An air inlet 4, which is communicated with the drawing tube 3, is provided in the drawing tube 3 in the neighborhood of its end portion 3b on the side of the outside of the granulating vessel 2. Through this air inlet 4, gas having higher pressure than the inside of the granulating vessel 2 is introduced into the drawing tube 3. By this, in the particle measurement device for the powder or granular processing apparatus, effects of remaining powder or granular material and flow out of the powder or granular material are removed, and grain size etc. are measured with high reliability.

TECHNICAL FIELD

The present invention relates to a particle measurement device for apowder or granular material processing apparatus, and in particular, totechniques effectively applicable to a grain size measurement devicewhich actually and continuously measures grain sizes, shapes, and thelike of powder or granular material produced by various powder orgranular material processing apparatuses such as a fluidized bedgranulator apparatus, an agitation granulator, a centrifugal tumblinggranulating/coating apparatus.

BACKGROUND ART

There are various processings of powder or granular material, includinggranulating, drying, coating, and the like. Among them, as thegranulating method of powder or granular material, can be listed thefluidized bed granulating method, agitation granulating method,centrifugal tumbling granulating method, and combinations thereof orcombined-type granulating methods, and they are widely employed invarious fields such as pharmaceutical preparations and food.

At first, among these granulating methods, the fluidized bed granulatingmethod comprises sprinkling liquid material on powder or granularmaterial, which has been in a fluidized state by dispersion and mixingwithin a processing vessel, increasing the grain sizes gradually. As afluidized bed granulating apparatus for such processing, may bementioned Flow Coater (trade name) by Freund Industrial Co., Ltd. whichfundamentally comprises a processing vessel for containing andprocessing material to be processed, a fluidizing air supply device forsupplying fluidizing air so as to fluidize the material, and a spraynozzle for spraying liquid on the material. By the fluidizing air, thematerial to be processed comes to be fluidized, and on this fluidizedmaterial, the liquid is sprayed by the spray nozzle, to carry out thegranulation.

Next, the agitation granulating method comprises dispersing and mixingsolid/liquid to produce particles, by agitation with an agitating blade(agitator). As an agitation granulating apparatus for such processing,be mentioned a high speed mixer FS-G model (trade name) of Fukae KogyoLtd., which is called, in another name, as a high speed mixing machine.As disclosed in Japanese Patent Publication No. 6-22667, Japanese PatentPublication No. 6-24619, Japanese Un-examined Patent Laid-Open No.5-236, and Japanese Patent Publication No. 2-32932, this agitatinggranulating apparatus fundamentally comprises an agitating bladerotatably provided within a processing vessel, with a bottom portion ofthe processing vessel serving as a fixed wall. In addition to thisconstruction, a disintegrating blade (chopper) may be provided ifnecessary, as shown in Japanese Un-examined Patent Laid-Open No.5-115766, so that disintegration granulation may be performed by thechopper, in addition to tumbling granulation by the agitator. Further,if a drying process is needed, a vacuum drying system may be provided,or otherwise, a heater may be provided on the outer periphery of theprocessing vessel in a jacketing manner. Then, by suitably controllingrotational speed of the agitator and the chopper, quantity of theliquid, quantity of charging, granulation time, temperature, and thelike, mixing granulation of the powder or granular material is carriedout.

On the other hand, the centrifugal tumbling method comprises tumblingmixing of powder material on a rotating disk, while spraying liquid onthe material to make powder particles adhere to and agglomerate with oneanother. As a centrifugal tumbling granulating apparatus for suchprocessing, be mentioned CF Granulator (trade name) made by FreundIndustrial Co., Ltd., an automatic coating apparatus described inJapanese Patent Publication No. 54-992, and a granulating apparatus ofJapanese Un-examined Patent Laid-Open No. 6-262054 (corresponding toU.S. Pat. No. 5,507, 871), and each of these apparatus fundamentallycomprises a rotating disk, which rotates generally horizontally,provided at a bottom portion of a processing vessel. If necessary, slitair is supplied into the inside of the processing vessel through aring-shaped gap formed between circumference of the rotating disk and ainside wall portion of the processing vessel, while dispersing powderand spraying liquid on the material to be processed within theprocessing vessel, so as to perform granulation of the powder orgranular material.

Further, there has been used the combined-type granulating method whichcombines the above-described techniques. For example, there has beenappeared an apparatus, such as Spir-A-Flow (trade name) made by FreundIndustrial Co., Ltd., which fundamentally performs the fluidized bedgranulation, and suitably combines it with the agitation granulation andthe centrifugal tumbling granulation, using combination of a rotor diskand an agitator.

In such process of granulating powder or granular material, from theviewpoint of the object of producing particles and from the viewpoint ofprocess validation for a product, measurement and control of particlediameter are so important as to be incomparable with the other factors.By this reason, various granulating apparatuses use a moisture meter, apressure gauge, an electric power meter, and the like as sensors forprocess validation. Using these sensors, an end of granulation,granulating conditions, and the like are controlled. Here, "processvalidation" is defined as "a documented program giving a high-levelassurance that a certain process constantly produces products compliantwith preset standard and quality characteristics", and is important fromthe viewpoint of GMP (Good Manufacturing Practice).

However, measurement using these sensors gives only indirect"estimation" of particle diameters, and has disadvantage that errorbecomes large. Further, according to a granulation method, theabove-described sensors may not be used. For example, in non-water typegranulation using ethanol, the moisture meter can not be used. Further,each granulating method has following specific difficulty.

First, in the fluidized bed granulating method, process controlgenerally uses an infrared absorption moisture meter such as Moiswatch(trade name) made by Okawaraseisakusho. Such a moisture meter, however,has disadvantages in that data is blurred in high moisture content area,and that variation of moisture content is smaller in comparison withvariation of particle diameter. Further, in the case of granulation withconstant moisture content, the end point of granulation can not bedecided by such a moisture meter.

Next, in the case of the agitation granulating method, although thereexist examples of validation using a pressure gauge or a resistancemeter or based on power consumption, granulation is generally controlledby charge amount of raw material, added amount of binder, rotation speedof the agitating blade, and agitating time. For example, in the case ofthe control by power consumption, power consumption rapidly increases atthe start of the granulation, repeats fluctuations as the granulationproceeds, decreases gradually as resistance to agitation decreases, andbecomes steady state as the regulation of particles proceeds, and,following these stages, the end point of the granulation is decided.However, synthetic process or storage conditions of the raw materialetc. may affect them so that the raw material etc. are varied in theirhygroscopic property (wettability), fluidity, and powder property(characteristics of bulk) such as agglomeration or adhesion propertyetc. Accordingly, for validation, it is desirable to control byfeedback. Further, as in the case of the control by power consumption,when granulation is made to proceed until change of load on agranulating apparatus becomes obvious, detection by a sensor is easy,but granulation tends to proceed excessively. In particular, in the caseof granulation for tabletting, the excessive granulation makes theparticles too hard, or produces too small amount of fine powder.

Further, in the centrifugal tumbling granulating method, an operatordecides the end point of the granulation by directly feeling watercontent in the powder material with his hand, or by observing sampledproducts with a magnifying lens, for example. Judgment, however, by theoperator's feeling or eye observation can not be said as objectivejudgment at all, and validation is impossible. On the other hand,although introduction of a moisture meter or a lever resistance typepressure gauge has been studied, a satisfactory result has not beenobtained since, for example, measurement error becomes large due toadherence of the powder material to an employed sensor such as amoisture meter. In particular, in the case of an electrode-type moisturemeter, powder adheres to surface of an electrode of the moisture meter,and the measurement becomes impossible in short time. In addition, amoisture meter or the like has been used mainly for maintaining of anequilibrium state of granulation process, and can not be used fordeciding an end point of granulation.

Thus, there are various disadvantages for control of granulation processin respective granulating methods. In particular, the fluidized bedgranulating method has a disadvantage in that variation in grain sizeand particle shape (referred to as "grain size etc." in abbreviation) ofproducts is large, and various grain size control methods have beentried for this granulating method.

In that case, to make the grain size etc. of powder or granular materialuniform, it is necessary to monitor the grain size etc. always in realtime for change of processing conditions at any time, and to suitablydecide an end point of processing for obtaining products with desiredproperties. For that purpose, as described above, such techniques astime management by timer control, observation by a skilled worker,control by water content value, and the like have been employed.However, the timer control or the observation by a skilled worker has aproblem in accuracy. Namely, the timer control can not cope with changein bulk characteristics, and variation in product grain size can not beavoided. Further, accuracy is lacked in workings depending on skilledworker's experience or perception such as judgment of the processingstate by observing the inside of a processing apparatus through itsinspection hole. Further, it is difficult to give exact judgment by thecontrol based on water content value, since change of water content doesnot quickly respond to rapid advance of granulation in the stageapproaching the end point of the granulation. Accordingly, in manyconventional cases, end of granulation is decided by judgment of grainsize etc. by eye observation or measurement of granulated objectssampled in the course of the granulation process. For example, the endpoint is predicted by sieving the sampled products with 16 mesh sievefor 10 seconds, and by calculating based on the ratio of the particlesremaining on the sieve.

Such a method, however, can not obtain data in real time, is inferior inaccuracy and rapidity, and, thus, is unfavorable from the viewpoint ofvalidity. Accordingly, to grasp, in real time, grain size etc. simplyand accurately, such grain size measurement devices have been proposedas described in Japanese Un-examined Patent Laid-Open No. 4-265142,Japanese Un-examined Patent No. 7-794, Japanese Un-examined PatentLaid-Open No. 7-120374, and Japanese Un-examined Patent Laid-Open No.8-131810.

Here, in the grain size measurement device of 4-265142, a processingvessel (granulating vessel) is provided with a drawing tube for powderor granular material, and high pressure gas is blown from the inside ofthe processing vessel to introduce the powder or granular materialwithin the processing vessel into the drawing tube. Thus-introducedpowder or granular material is captured by adhesive film provided in aninner part of the drawing tube, and an image of the captured powder orgranular material is picked up to measure its grain size etc. After themeasurement of the grain size, the inside of the drawing tube for powderor granular material is cleaned by negative pressure in the processingvessel. On the other hand, in the device of 7-794, a camera device and ahigh speed stroboscopic device are provided being directed toward theinside of the processing vessel, and, using these devices, a staticimage is obtained to measure grain size etc.

Further, as for the camera devices for granulation, coating, or the likein 7-120374 and 8-131810, camera system devices and lighting systemdevices are arranged within the processing vessel, and powder orgranular material is made to be in a separated state by air and, then,is photographed. In that case, in the camera device of 7-120374, frontend portions of the camera system and the lighting system are providedadjacently within the processing vessel, and air is supplied in thedirection of photographing and in the direction at right angles with theformer to put the powder or granular material in the separated state. Onthe other hand, in 8-131810, lighting and air injection are givenobliquely in front of a lens tube containing the camera system, thusputting the powder or granular material in dispersed condition to take apicture.

Although these devices, in particular the grain size measurement deviceof 4-265142, are superior ones which can measure grain size etc. in realtime simply and accurately, when the inside of the processing vessel isnot at negative pressure, sometimes a great amount of powder or granularmaterial adheres to the adhesive film so that it becomes impossible tomeasure. Further, the powder or granular material introduced in the lasttime remains within the drawing tube, and adheres to the adhesive filmtogether with the powder or granular material introduced in the nexttime so that accurate sample can not be obtained.

Further, at the time of measurement, the adhesive film for capturing thepowder or granular material is tightly fixed to the drawing tube. Fornext measurement, however, it should be once separated from the drawingtube and wound, so that unused portion of the film is moved to thesuitable position. Thus, at the time of the movement of the film, thereexist gaps between the adhesive film and the drawing tube for powder orgranular material, and the powder or granular material flows out throughthese gaps, contaminating adjacent portions of the device and an unusedportion of the adhesive film. In that case, the flowed-out powder orgranular material is scattered onto the image pick-up means forobtaining sampling images, having an adverse effect on subsequentpick-ups and measurements, or making measurement itself impossible, andsettlement of these problems has been desired.

On the other hand, the devices of 7-120374 and 8-131810 photographparticles by dispersing them with purging air. Thus, in an apparatuswhere particles are floated such as the fluidized bed apparatus, it ispossible to disperse the particle, and the device of 7-120374 or8-131810 can be used without problem for photographing particles.However, in the agitation granulating apparatus and the centrifugaltumbling granulating apparatus, a great amount of particles are in aconcentrated state, and it is difficult to disperse the particles toidentify an individual, and the device of 7-120374 or 8-131810 can notbe applied to such a kind of granulating apparatus.

An object of the present invention is to provide a particle measurementdevice which can perform real-time and highly-reliable measurement ofgrain size etc. in various granulating apparatuses.

The above-described and other objects and new features of the presentinvention will be obvious from the following description and theattached drawings.

DISCLOSURE OF THE INVENTION

The inventor of the present invention has studied the cause of theabove-described problems to find that the number of powder or granularmaterial captured by adhesive film is largely affected by air pressureinside a processing vessel. Namely, owing to pressure fluctuation insidethe processing vessel, occasional adhesion of a great amount of powderor granular material to the adhesive film arises since a drawing tubefor powder or granular material is not cleaned sufficiently by negativepressure inside the processing vessel, and since the powder or granularmaterial intrudes into the drawing tube at other times than themeasurement time.

The particle measurement device of the present invention can be utilizedin various apparatuses which perform general processing of powder orgranular material such as granulating, drying, coating, or the like,including a fluidized bed granulating apparatus, a fluidized bed coatingapparatus, a fluidized bed drying apparatus, an agitation granulatingapparatus, a centrifugal tumbling granulating apparatus, a centrifugaltumbling coating apparatus, other combined-type granulating apparatuses,a powder or granular material extrusion granulating apparatus, acrusher, a powder or granular material recovery apparatus, and aparticle regulating apparatus. Among such various apparatus forprocessing powder or granular material, in the apparatus utilizing thefluidized bed, such as the fluidized bed granulating apparatus, thefluidized bed coating apparatus, the fluidized bed drying apparatus, andthe like, fluidizing air flow is generated by an exhaust blower, andaccordingly the inside of the processing vessel is negative pressure incomparison with the outside air. Further, the end portion of the drawingtube for powder or granular material is sealed by adhesive film exceptfor winding time. Thus, it has been considered that the powder orgranular material does not flow into the inside of the drawing tube forpowder or granular material except that the powder or granular materialis introduced into the drawing tube by gas injection from the inside ofthe processing vessel. Further, it has been considered that the powderor granular material remaining within the drawing tube is sucked back bythe negative pressure of the processing vessel when the seal by theadhesive film is released.

However, studies by the present inventor have revealed facts that theair pressure inside the processing vessel is not constant, butfluctuates in a wider range; that, owing to this pressure fluctuation,the powder or granular material flows into the drawing tube at othertimes than the measurement times, and cleaning is insufficient at times;and that, owing to these factors, the number of the captured powder orgranular material is varied at measurement times. Thus, to prevent suchflowing-into of the powder or granular material, and to remove theeffect of the powder or granular material remaining in the drawing tube,the present inventor has completed the present invention.

Out of the inventions disclosed here, outlines of representative oneswill be briefly described as follows.

Namely, a particle measurement device for a powder or granular materialprocessing apparatus, according to the present invention, has a drawingtube for drawing out powder or granular material, provided in agranulating vessel, in such a manner that one end portion of the drawingtube is arranged in the inside of the processing vessel, and that theother end portion is communicated with said one end portion andpositioned in the outside of the processing vessel. Further, the presentdevice comprises a gas injection nozzle for injecting high pressure gasfrom the inside of the processing vessel into the drawing tube, so as tointroduce the powder or granular material within the processing vesselinto the drawing tube. Further, the device comprises an adhesive filmwhich has an adhesive surface arranged opposed to an opening of an endsurface of the drawing tube on the side of the outside of the processingvessel, so as to capture, with said adhesive surface, the powder orgranular material which has passed the drawing tube; an image pick-upmeans for photographing the powder or granular material captured by theadhesive surface of the adhesive film; and an information processingmeans for processing image information of the powder or granularmaterial obtained by the image pick-up means. The device ischaracterized in that, in the neighborhood of the end portion of thedrawing tube on the side of the outside of the processing vessel, isprovided an air inlet communicated with the drawing tube, and gas havinghigher pressure than the inside of the processing vessel is introducedinto the drawing tube through the air inlet.

Further, in order to remove effects by powder or granular materialflowing out from the drawing tube, in the particle measurement devicefor a powder or granular material processing apparatus, such asdescribed above, comprising a drawing tube, a gas injection nozzle, anadhesive film, an image pick-up means, and an information processingmeans, the adhesive film and the end portion of the drawing tube opposedto the adhesive film may be housed within a box having an air feed port,so as to introduce gas, which has higher pressure than the inside of theprocessing vessel, into the box through the air feed port. In that case,an air communicating port communicated with the drawing tube may beprovided in the neighborhood of the end portion of the drawing tube, insuch a manner that this air communicating port is housed within the boxtogether with the adhesive film and the end portion of the drawing tubeopposed to the adhesive film.

By this construction, in the particle measurement device which employssuch a method of measuring grain size etc. of the powder or granularmaterial that the powder or granular material is introduced into thedrawing tube, captured by the adhesive film, and photographed, effectsof the powder or granular material remaining in the drawing tube and thepowder or granular material flowing out from the tube can be eliminated.

The above-described powder or granular material processing apparatus maybe a fluidized bed granulating apparatus or a fluidized bed coatingapparatus, a fluidized bed drying apparatus, an agitation granulatingapparatus, a centrifugal tumbling granulating apparatus, or acentrifugal tumbling coating apparatus. In that case, of course, theparticle measurement device according to the present invention can beapplied to a powder or granular processing apparatus other than theabove-described granulating apparatuses, the coating apparatuses, andthe drying apparatus, namely, to such processing apparatuses as, forexample, a powder or granular material extrusion granulating apparatus,a crusher, a powder or granular material recovery apparatus, a powder orgranular material regulating apparatus and the like.

Further, the above-described particle measurement device may beinstalled downstream from the powder or granular material processingapparatus which can perform continuous processing of the powder orgranular material, so as to control processing conditions of theabove-described powder or granular material processing apparatus basedon a result of the measurement by the particle measurement device. Inthat case, the particle measurement device may be installed in a powderor granular material transport pipe arranged between powder or granularmaterial processing apparatuses.

On the other hand, a method of particle measurement for a powder orgranular material processing apparatus, according to the presentinvention, is one which uses the above-described particle measurementdevice provided with the air inlet, and in that method, high pressuregas is injected from the gas injection nozzle so as to introduce powderor granular material inside the processing vessel into the drawing tube;the powder or granular material which has passed the drawing tube iscaptured by the adhesive surface of the adhesive film; and the powder orgranular material captured by the adhesive film is photographed toobtain image information, and, based on the obtained image information,information on the powder or granular material within the processingvessel is obtained. In that method, the particle measurement isperformed while gas having higher pressure than the inside of theprocessing vessel is always introduced into the drawing tube through theair inlet. In that case, the measurement is performed in such a statethat the powder or granular material remaining in the drawing tube isreturned into the processing vessel by the introduced gas, and thepowder or granular material does not enter into the drawing tube fromthe side of the processing vessel except for measurement time.

Further, the present invention provides a method of particlemeasurement, using the above-described particle measurement device inwhich the adhesive film and the end portion of the drawing tube opposedto the adhesive film are housed in the box having the air feed port, andin that method, the particle measurement is performed while the adhesivefilm is tightly fixed to an end surface of the drawing tube, and theadhesive film is separated from the end surface and exchanged for anunused adhesive film, at every end of the measurement. And, byintroducing the gas having the higher pressure than the inside of theprocessing vessel into the box through the air feed port at least whenthere is a gap between the adhesive film and the drawing tube, theinside of the box is kept at higher pressure than the inside of theprocessing vessel.

Further, the present invention provides a method of particlemeasurement, using the particle measurement device which is providedwith an air communicating port also housed in the above-described box,and in this method, the particle measurement is performed while the gashaving the higher pressure than the inside of the processing vessel isalways introduced into the box through the air feed port so as to keepthe inside of the box at higher pressure than the inside of theprocessing vessel.

The above-described powder or granular material processing apparatus maybe a fluidized bed granulating apparatus or a fluidized bed coatingapparatus, a fluidized bed drying apparatus, an agitation granulatingapparatus, a centrifugal tumbling granulating apparatus, or acentrifugal tumbling coating apparatus. In this case too, of course, theparticle measurement device according to the present invention can beapplied to a powder or granular processing apparatus other than theabove-described granulating apparatuses, the coating apparatuses, andthe drying apparatus, namely, to such processing apparatuses as, forexample, a powder or granular material extrusion granulating apparatus,a crusher, a powder or granular material recovery apparatus, a powder orgranular material regulating apparatus and the like.

Further, the present invention provides a method of controlling a powderor granular material processing apparatus, characterized in that theabove-described particle measurement device is installed downstream froma powder or granular material processing apparatus which can performcontinuous processing of the powder or granular material, and processingconditions of the powder or granular material processing apparatus arecontrolled based on a result of the measurement by the particlemeasurement device. In that case, the particle measurement device may beinstalled in a powder or granular material transport pipe arrangedbetween the powder or granular material processing apparatuses.

Further, a program for making a computer execute the above-describedmethod according to the present invention may be stored and handled in amedium.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partially sectional plan view showing construction of aparticle measurement device for a powder or granular material processingapparatus, as a first embodiment of the present invention;

FIG. 2 is an explanatory view showing a state where the particlemeasurement device of FIG. 1 is attached to the powder or granularmaterial processing apparatus;

FIG. 3 is a block diagram showing construction of a control part of theparticle measurement device of FIG. 1;

FIG. 4 is a flowchart showing an outline of operation in the case thatgranulation control of powder or granular material is performed usingthe particle measurement device of FIG. 1;

FIG. 5 is a partially sectional plan view showing construction of aparticle measurement device for a powder or granular material processingapparatus, as a second embodiment of the present invention;

FIG. 6 is a partially sectional plan view showing construction of aparticle measurement device for a powder or granular material processingapparatus, as a third embodiment of the present invention;

FIG. 7 is an explanatory view showing an example as a fourth embodimentof the present invention, in which the particle measurement device ofFIG. 1 is attached to an agitation granulating apparatus;

FIG. 8 is an explanatory view showing a variation of the example shownin FIG. 7;

FIG. 9 is an explanatory view showing an example in which the particlemeasurement device of FIG. 1 is attached to a centrifugal tumblinggranulating apparatus, as a fifth embodiment of the present invention;

FIG. 10 is an explanatory view showing an example of a system in whichfeedback control is performed on a powder or granular materialprocessing apparatus, by using the particle measurement device of FIG.1, as a sixth embodiment of the present invention;

FIG. 11 is an explanatory view showing a variation of the example ofFIG. 10;

FIG. 12 is a graph showing time variations of average particle diameterand content of particles with 75 μm-or-less diameter in the batch No. 1;

FIG. 13 is a graph showing grain size distributions for batches Nos. 1-3obtained by a low tap sieve shaker; and

FIG. 14 is a graph showing comparison between granulated productsobtained in the case that control of granulation end point is performedusing the particle measurement device of the present invention andgranulated products obtained in the case that control of granulation endpoint is performed by the conventional method.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, embodiments of the present invention will be described in detailreferring to the drawings.

FIG. 1 is a plan view showing construction of a particle measurementdevice for a powder or granular material processing apparatus, asEmbodiment 1 of the present invention; and FIG. 2 is an explanatory viewshowing a state in which the particle measurement device of FIG. 1 isattached to the powder or granular material processing apparatus. Inthis FIG. 1, a part of the construction is shown in section. In thisEmbodiment 1, the powder or granular material processing apparatus isassumed to be a fluidized bed granulating apparatus. Further, a drawingtube 3 of the particle measurement device 1 for drawing the powder orgranular material is provided with an air inlet 4 for cleaning theinside of the tube. By introducing clean gas through this air inlet 4,the powder or granular material remaining within the drawing tube 3 isreturned into the inside of a granulating vessel (processing vessel) 2so that the inside of the drawing tube 3 is cleaned and, at the sametime, intrusion of the powder or granular material from the granulatingvessel 2 into the drawing tube is prevented.

First, construction of the particle measurement device 1 in Embodiment 1will be described. This particle measurement device 1 measures grainsize etc. of the powder or granular material being fluidized within thegranulating vessel 2 of the fluidized bed granulating apparatus (powderor granular material processing apparatus) 20. As shown in FIGS. 1 and2, the particle measurement device 1 is mounted onto a side wall 21 ofthe granulating vessel 2 having an inverted cone shape with an upperportion being of larger diameter. The mounting location of the device isnot limited to the surface of the side wall 21, though it is preferablethat the particle measurement device 1 is mounted at a place where graindensity is high.

Here, the powder or granular material fluidized within the granulatingvessel 2 is affected by air classification, and grain size distributionvaries with the location within the fluidized bed. The powder orgranular material in a lower portion of the fluidized bed shows adistribution generally similar to population, while, in a upper portionof the fluidized bed, a distribution is one including more fineparticles. Accordingly, it is preferable that measurement of grain sizeetc. aims at the powder or granular material existing in the lowerportion of the fluidized bed. To that end, as shown in FIG. 2, theparticle measurement device 1 in question is mounted on a relativelylower portion of the granulating vessel 2. Of course, the mountinglocation is not limited to the one shown in FIG. 2.

The particle measurement device 1 is so provided with the drawing tube 3of a cylindrical shape that the drawing tube is projected from theinside of the granulating vessel 2 to the outside. An end portion 3a ofthe drawing tube 3 is opened toward the inside of the granulating vessel2 so that the drawing tube 3 is communicated with the inside of thegranulating vessel 2.

Further, the fluidized bed granulating apparatus 20 is common one inwhich fluidizing air 23 is introduced into the fluidized bed granulatingapparatus 20 from an under side of a perforated plate 22 provided in abottom portion of the apparatus 20, and, by this, the powder or granularmaterial 24 is fluidized and granulated within the granulating vessel 2.Of course, the particle measurement device 1 in question can be appliedto various fluidized bed granulating apparatus such as one disclosed inJapanese Un-examined Patent Laid-Open No. 6-319978, for example.

In Embodiment 1, the air inlet 4 is provided in the neighborhood of anend portion 3b located in the drawing tube 3 on the side of the outsideof the granulating vessel 2. This air inlet 4 is communicated with thedrawing tube 3, and gas introduced through the air inlet 4 passes thedrawing tube 3 to flow into the granulating vessel 2. In Embodiment 1,clean gas is introduced through the air inlet 4 into the drawing tube 3.By this clean gas, the powder or granular material remaining in theinside of the drawing tube 3 is returned into the inside of thegranulating vessel 2 so that the inside of the drawing tube 3 iscleaned.

In the neighborhood of the end portion 3a of the drawing tube 3, a gasinjection nozzle 5 is mounted. The gas injection nozzle 5 is so crudelyarranged that a tip of the nozzle 5 is opposed to an opening of the endportion 3a of the drawing tube 3. High pressure gas is supplied from agas supply means not shown, and the high pressure gas is injectedinstantaneously from the tip toward the drawing tube 3. By thisinjection, the powder or granular material in the granulating vessel 2is introduced into the drawing tube 3, and scattered toward the endportion 3b.

On the other hand, the end portion 3b on the side of the outside of thedrawing tube 3 is opened toward the outside of the granulating vessel 2,and adhesive film 6 is arranged to be opposed to an end surface 3c ofthe end portion 3b. The adhesive film 6 is formed of transparent resintape coated with also transparent adhesive material on one surface ofthe tape, and is placed so that the adhesive surface is opposed to theend surface 3c. Namely, the powder or granular material introduced intothe drawing tube 3 by the injection from the gas injection nozzle 5, iscaptured by the adhesive tape 6 in this area.

The adhesive film 6 is one wound in a roll shape, supported by a rollsupporting portion 71, and intermittently drawn out by given length inaccordance with measurement of the powder or granular material. Aftermoving along the end surface 3c of the drawing tube 3 through guiderollers 73, 73, the adhesive film 6 is wound by a motor reel 72. At thattime, the adhesive film 6 is tightly fixed to the end surface 3c whenthe powder or granular material is measured, and, after the end of themeasurement, is peeled from the end surface 3c, and is wound inpreparation for the next measurement. Then, an unused portion of theadhesive film 6 is moved to the position opposed to the end surface 3c,and is tightly fixed to the end surface 3c again.

For tightly fixing the adhesive film 6, there may be employed variousmethods such as one that a transparent or frame-shaped push plate or thelike is pushed against the adhesive film 6 at the back of the film 6, ora method utilizing the tensile force of the adhesive film 6. InEmbodiment 1, this is done by driving a film keep plate 14 with an aircylinder 15. Namely, the air cylinder 15 pushes the film keep plate 14against the back of the adhesive film 6, so that the adhesive film 6 ispushed against the end surface 3c of the drawing tube 3 so as to betightly contacted with the end surface 3c. As a result, the drawing tube3 is kept in a sealed state by the adhesive film 6 except when theadhesive film 6 is wound.

For adjusting winding length of the adhesive film, the particlemeasurement device 1 of Embodiment 1 in question is provided with asensor 16 for detecting movement of the guide roller 73. This sensor 16comprises a proximity switch, and detects passing of a hole 17 formed inthe guide roller 73. Accordingly, by counting the number of passing ofthe hole 17, the number of rotation of the guide roller 73, which isrotated by bearing the adhesive film 6, can be obtained, and movement ofthe adhesive film 6 can be calculated from the number of rotation.

The adhesive film 6 has such a property that a widthwise stripe isproduced in the adhesive surface of the film 6 at the time of itsstopping. Namely, as in the cases of cellophane tape and vinyl tape, thewidthwise stripe is produced on the boundary between a part peeled fromthe roll for supplying the adhesive film 6 and a part which has not beenpeeled. When such a stripe comes within an image pick-up range for acamera, it affects the identification of particles of the powder orgranular material, and obstructs data processing. By this reason, inthis particle measurement device 1, the movement of the adhesive film 6is detected by using the above-described sensor 16, to adjust thewinding length of the adhesive film 6 so that the above-described stripedoes not come within the image pick-up range and, at the same time, theadhesive film 6 can be used as effectively as possible.

Behind the adhesive film 6, for lighting the adhesive film 6, a circularfluorescent lamp 8 is provided being supported by a fluorescent lampsupporting portion 11. Further, behind the fluorescent lamp 8, isinstalled a CCD camera 7 (image pick-up means) for picking up a state ofthe powder or granular material adhering to the adhesive film 6. Thefluorescent lamp supporting portion 11 is shielded for the light on itssurface on the side of the CCD camera 7 so that the light of thefluorescent lamp 8 does not enter the CCD camera 7 directly. The pick-updata is transmitted to a control part (information processing unit) 12,and grain sizes etc. of all the powder or granular material adhering tothe adhesive film 6 are measured.

Here, the control part 12 is a part which performs image processing andcontrol of the system as a whole, and, as shown in FIG. 3, comprises animage processing unit 31, a sequencer 32, and a panel computer 33. Theimage processing unit 31 processes a particle image from the CCD camera7. The sequencer 32 obtains measurement data from the sensor 16, andcontrols the gas injection nozzle 5, the CCD camera 7, the air cylinder15, the motor reel 72, and the like, to make them perform samplingoperation and image pick-up operation. Further, the sequencer 32 alsocontrols operation of the fluidized bed granulating apparatus 20.Further, the panel computer 33 receives data from the image processingunit 31 to perform various calculations, and controls the sequencer 32.

In addition, the control part 12 is equipped with an analysis monitor 34for displaying a particle image undergone the image processing, so thata state of measurement of particle can be checked. Further, a colormonitor 35, which displays images from the CCD camera 7, is alsoprovided to the control part 12 so that colors, shapes and surfaceconditions of particles can be observed from the raw images of theparticles. In addition, the control part 12 is equipped with a videotape recorder 36 for recording those images. Further, a printer 37 forprinting out analysis results etc., and a hard disk as a storage meansfor storing various data such as the analysis results etc. are providedto the control part 12.

On the other hand, in the control part 12, measurement of particlediameter is performed as follows. Namely, first, in the image processingunit 31, analogue image sent from the CCD camera 7 is divided into500×500 (=250,000) pixels, for example, and each pixel is digitized intoa binary digit depending on its luminous intensity. This data is sent tothe panel computer 33. Then, based on the received data, the panelcomputer 33 defines a projected area of a particle as an area ofhigh-level pixels which continuously contact with one another, obtains adiameter of a supposed circle having the same area as the such-definedprojected area, and gives this diameter as particle diameter data. Fromthus-obtained particle diameter data, grain size distribution, anaverage particle diameter, and the like are calculated. Further, fromthe projected particle image, a major diameter and a minor diameter aremeasured, and also a sphericity (ratio of the major diameter to theminor diameter) is calculated. With respect to these controls of thevarious devices by the control part 12 and calculations of the particlemeasurement through the image analysis by the control part 12, programsfor the computer to execute these operations may be stored and handledin a medium.

Next, operation of Embodiment 1 will be described. FIG. 4 is a flowchartshowing an outline of the operation in the case that granulation controlof powder or granular material is performed using the particlemeasurement device 1. Also, it is to be noted that programs may bestored and handled in a medium, so that, by these programs, the computerexecutes a procedure for measurement of powder or granular material, aprocedure for deciding end of granulation, and granulation control,described below.

As shown in FIG. 4, in the particle measurement device 1 in question,first, sampling of the powder or granular material is performed (S1),and grain sizes etc. of the samples are measured (S2). Next, it isjudged if the measured values arrive at preset values (S3). When theyarrive at the preset values, the granulation is stopped (S4), and dryingand discharging of the products are performed (S5). On the other hand,when they do not arrive at the preset values, the granulation operationis continued, and sampling is repeated at given time intervals (S1).

Here, first, in the particle measurement device 1 of Embodiment 1, gasfor cleaning the drawing tube 3 is introduced always from the air inlet4 into the drawing tube 3, so that air flow toward the granulatingvessel is always produced within the drawing tube 3. On the other hand,when granulation is performed in the fluidized bed granulatingapparatus, powder or granular material having various grain sizes etc.is fluidized to form a fluidized bed within the granulating vessel 2,and the inside of the granulating vessel 2 is at negative pressureslightly lower than the atmospheric pressure, although there existslarge fluctuation of that negative pressure as described above.

Accordingly, in Embodiment 1, feeding quantity of the gas from the airinlet 4 and pressure difference from the inside of the granulatingvessel 2 are set within suitable ranges, in order that pressure of theinside of the drawing tube 3 may not be lower than the pressure insidethe granulating vessel 2 regardless of the pressure fluctuation insidethe granulating vessel 2, and that high pressure gas injection from thegas injection nozzle 5 may cause a suitable number of powder or granularmaterial to be captured by the adhesive film 6. By this, it is possibleto suitably control the number of the powder or granular materialadhering to the adhesive film 6, in the drawing tube 3 of Embodiment 1.In that case, supply pressure of the gas is set generally in the rangeof 0.5-5 kg/cm2, and preferably in the range of 0.1-3 kg/cm2.Preferably, the supply gas may be same as the gas existing inside thegranulating vessel 2 although any gas may be used, and usually, air,i.e., atmospheric air is supplied.

Next, while the gas is introduced from the air inlet 4, high pressuregas is injected from the gas injection nozzle 5 so that the powder orgranular material is introduced into the drawing tube 3. Here, thepressure of the gas injected from the gas injection nozzle 5, as well asthe pressure of the gas introduced from the air inlet 4, is so adjustedto be a suitable value that the powder or granular material floatingabout the tip of the gas injection nozzle 5 arrives at the adhesive film6. By this injection, all the powder or granular material floating infront of the gas injection nozzle collides against the adhesive film 6through the drawing tube 3 and adheres to its adhesive surface. Theinjection of the high pressure gas may be suitably set, for example, insuch a way that it is performed at given time intervals or at optionallypredetermined times.

At the end of the gas injection, the CCD camera 7 takes a picture of theadhesive film 6 to which the powder or granular material adheres, withlighting of the fluorescent lamp 8, and the data is output into thecontrol part 12. In the control part 12, for all the powder or granularmaterial adhering to the adhesive film 6, grain sizes etc. are measuredin the above-described manner. This means that the grain sizes etc. ofthe powder or granular material being fluidized at the time ofgranulation within the granulating vessel 2 are directly measured inreal time.

The control of the granulation end point is performed by using data ofgrain size and sphericity, for example. In that case, the end pointvalue or values are set for predetermined one or more factors, and atime point when actual measurement arrives at the set value is regardedas the granulation end point and the process in question is ended.

On the other hand, as for the time interval for the particlemeasurement, there may be set some modes such as a standard measurementmode, a high speed measurement mode, a programmed mode, and the like. Inthat case, in the standard measurement mode, for example, all thefactors relating to particle diameter and sphericity are calculated, andthe measurement interval can be selected in the range of 10-99 seconds.In the high speed mode, only data relating to particle diameter ismeasured, and the measurement interval is fixed to 5 seconds. Further,in the programmed mode, the measurement interval and frequency can beset freely and suitably.

After such measurement, the motor reel 72 is driven to draw out theadhesive film 6 by one pitch length. At that time, the adhesive film 6with the adhered powder or granular material is peeled from the endsurface 3c of the drawing tube 3 for the powder or granular material,and an unused portion of the film 6 is moved to a position opposed tothe end surface 3c and tightly fixed to the end surface 3c, completingpreparation of the next measurement. Control of these operations isperformed also by the control part 12.

Thus, according to the particle measurement device 1 of Embodiment 1,the inside of the drawing tube 3 for powder or granular material isalways kept clean by introducing gas at suitable pressure from the airinlet 4, and the number of the powder or granular material adhering tothe adhesive film 6 can be controlled. The lower portion of thefluidized bed is crowded with the powder or granular material, and it isvery difficult to identify individual particle by direct photographingof the crowded fluidized bed. However, according to the particlemeasurement device of the present invention, it is possible to measurethe powder or granular material in the lower portion of the fluidizedbed representing the population. Thus, irrespective of pressurefluctuation within the granulating vessel 2, accurate samples can beobtained always, and reliability of the measurement result is improved.

Next, there will be described a particle measurement device for a powderor granular material processing apparatus, as Embodiment 2 of thepresent invention. FIG. 5 is a plan view showing its construction. Alsoin FIG. 5, a part of the device is shown in section, as in FIG. 1.

As shown in FIG. 5, the particle measurement device 1 of Embodiment 2has fundamental construction similar to the particle measurement device1 of the previous Embodiment 1, except that a cover 9 covers a part onthe outward side of the end portion 3b of the drawing tube 3. Namely, asseen from FIG. 5, the cover 9 contains the end portion 3b of the drawingtube 3, the adhesive film 6, the roll supporting portion 71, the motorreel 72, the guide rollers 73, 73, the fluorescent lamp 8, thefluorescent lamp supporting portion 11, and the CCD camera 7. The samereference numerals are given to parts common to Embodiment 1, anddescription of details of them is omitted in the following. Further, inthe present embodiment, tensile force of the adhesive film is utilizedfor tightly fixing the film 6.

The cover 9 of Embodiment 2 is provided with an air feed port 10communicated with the inside space of the cover 9 for cleaning theinside of the cover 9. The cover 9 is fitted to the drawing tube 3,being tightly coupled to the end portion 3b of the drawing tube 3, so asto realize sealed structure which is only opened at the air feed port 10and the opening of the drawing tube 3. Accordingly, when the adhesivefilm 6 is tightly fixed to the end surface 3c, the inside of the cover 9becomes a sealed space except for the opening of the air feed port 10.

In thus-constructed particle measurement device 1, similarly toEmbodiment 1, the particle measurement is performed while cleaning theinside of the drawing tube 3 by introducing the gas through the airinlet 4. Operation at that time is similar to the case of Embodiment 1,and its detailed description is omitted. Then, after the particlemeasurement, the adhesive film 6 is moved by one pitch length forpreparing the next measurement. At that time, the adhesive film 6 ispeeled from the end surface 3c of the drawing tube 3 to be released fromthe tight condition before the movement, and, accordingly, there may bea gap between them and the powder or granular material may flow outthrough the gap.

Thus, in this Embodiment 2, at the time of the above-described movement,gas having slightly higher pressure than the inside of the granulatingvessel 2 is introduced into the inside of the cover 9 through the airfeed port 10. Namely, at least when there exists the above-describedgap, the gas is introduced so that the inside of the cover 9 is alwaysat higher pressure than the inside of the drawing tube 3. Thus, in thegap between the end surface 3c of the drawing tube 3 and the adhesivefilm 6, is produced air flow toward the drawing tube 3 only, and thepowder or granular material is prevented from flowing out from thedrawing tube 3 to the cover 9. In that case, although the pressure ofthe gas introduced through the air feed port 10 varies depending on themodel of the granulating apparatus, and the like, generally gas withpressure in the range of 0.05-5 kg/cm2, and preferably of 0.1-3 kg/cm2is introduced.

Although it is sufficient that the gas is introduced through the airfeed port 10 at least when the adhesive film 6 is moved, the inside ofthe cover 9 may always or suitably be kept at constant pressure slightlyhigher than the inside of the granulating vessel 2. In that case, whenthe gas is introduced, the adhesive film 6 is pressed against the endsurface 3c of the drawing tube 3, so that the adhesive film 6 can betightly in contact with the end surface 3c without employing other tightfixing means.

Thus, the present Embodiment 2 is constructed so that the cover 9contains the part on the outward side of the end portion 3b of thedrawing tube 3, including the fluorescent lamp 8 and the CCD camera 7.However, to prevent flow out of the powder or granular material throughthe gap, it is sufficient that, at minimum, the portion of the gap,i.e., the portion of the adhesive film 6 and the end surface 3c iscovered by the cover 9. It, however, is convenient from the viewpointsof dust protection and of device construction that the cover 9 containsthe CCD camera 7 etc. too.

As described above, according to the particle measurement device 1 ofEmbodiment 2, the cover 9 covers the portion between the end surface 3cof the drawing tube 3 and the adhesive film 6, and the inside of thecover 9 is set at slightly higher pressure than the inside of thegranulating vessel 2, so that flow out of the powder or granularmaterial through the gap therebetween can be prevented and the devicecan be kept in clean condition. In particular, the effect of preventingthe flow out of the powder or granular material is large in the casethat, in the neighborhood of the end portion 3a of the drawing tube,internal pressure of the fluidized bed on the side of the granulatingvessel 2 becomes positive pressure.

Thus, in Embodiment 2, there has been described the case that thepresent invention is applied to the particle measurement device 1provided with the air inlet 4. Of course, however, the above-describedconstruction can be applied to an apparatus without the air inlet 4.

Next, there will be described a particle measurement device for a powderor granular processing apparatus, as Embodiment 3 of the presentinvention. FIG. 6 is a partially sectional plan view showing itsconstruction.

As shown in FIG. 6, the particle measurement device 1 of Embodiment 3has fundamental construction similar to the particle measurement device1 of the previous Embodiment 2. Differently, however, from Embodiment 2,Embodiment 3 is provided with an air communicating port 13, instead ofthe air inlet 4, in the end portion 3b of the drawing tube 3 at itsportion covered by the cover 9, and the part on the outer side from thisair communicating port 13 is covered by the cover 9. Namely, as seenfrom FIG. 6, the cover 9 contains the end portion 3b of the drawing tube3 and the air communicating port 13 provided therein, the adhesive film6, the roll supporting portion 71, the motor reel 72, the guide rollers73, 73, the fluorescent lamp 8, the fluorescent lamp supporting portion11, and the CCD camera 7. Also, like reference numerals will be given tolike parts common to the previous Embodiments 1 and 2, and theirdetailed description will be omitted.

Here, the cover 9 of Embodiment 3 is provided with an air feed port 10communicated with the inside space of the cover 9. Further, this airfeed port 10 is communicated with the air communicating port 13 and thedrawing tube 3 through the inside space of the cover 9. Similarly toEmbodiment 2, the cover 9 is fitted to the end portion 3b of the drawingtube 3 in a tightly coupled state, and gives sealed construction exceptfor the air communicating port 13 and the opening of the drawing tube 3.Thus, when the adhesive film 6 is tightly fixed to the end surface 3c ofthe drawing tube 3, the inside of the cover 9 becomes a sealed spacewith the air communicating port 13 and the air feed port 10 arecommunicated with each other.

In thus-constructed particle measurement device 1, gas at given pressureis always introduced through the air feed port 10 so that the pressureinside the cover 9 is slightly higher than the pressure inside thegranulating vessel 2. In that case, feeding quantity of the gasintroduced from the air feed port 10 and pressure difference from theinside of the granulating vessel 2 are set so that the pressure insidethe cover 9 is slightly higher than the pressure inside the granulatingvessel 2 regardless of pressure fluctuation within the granulatingvessel 2, and so that the pressure inside the drawing tube 3 does notbecome lower than the pressure inside the granulating vessel 2 and theadhesive film 6 captures a suitable number of the powder or granularmaterial by high pressure gas injection from the gas injection nozzle 5.Although such pressure at the air feed port 10 varies depending on amodel of the granulating apparatus etc., it is generally in the range of0.05-5 kg/cm2, and preferably in the range of 0.1-3 kg/cm2, for example.

Since the cover 9 is closed in the state that the air communicating port13 and the air feed port 10 are communicated with each other, at thesame time when gas is introduced through the air feed port 10, the gasis introduced into the drawing tube 3 through the air communicating port13. Thus, the air communicating port 13 serves similarly to the airinlet 4 of Embodiment 1, and there are realized conditions similar toEmbodiment 1. Namely, by this introduction of the gas, the powder orgranular material remaining within the drawing tube 3 is returned intothe granulating vessel 2, and the powder or granular material isprevented from flowing from the granulating vessel 2 into the drawingtube 3. Under such conditions, similarly to Embodiments 1 and 2, highpressure gas is injected from the gas injection nozzle 5 to perform theparticle measurement. Operation at the time of the particle measurementis similar to the cases of Embodiments 1 and 2, and its detaileddescription is omitted here.

After the particle measurement, the adhesive film 6 is moved. In thepresent Embodiment 3, the gas at slightly higher pressure than theinside of the granulating vessel 2 is always introduced into the insideof the cover 9 through the air feed port 10, so that the inside of thecover 9 is always kept at higher pressure than the inside of the drawingtube 3. Namely, there are realized conditions similar to Embodiment 2.Thus, similarly to Embodiment 2, at the gap between the end surface 3cof the drawing tube 3 and the adhesive film 6, only air flow toward thedrawing tube 3 is produced, and flow out of the powder or granularmaterial from the drawing tube 3 toward the adhesive film 6 isprevented.

Thus, according to the particle measurement device 1 of Embodiment 3,the inside of the drawing tube 3 is always kept clean, and flow out ofthe powder or granular material through the gap between the end surface3c of the drawing tube 3 and the adhesive film 6 is prevented.

Next, as Embodiment 4 of the present invention, there will be shown anexample in which the particle measurement device of FIG. 1 is mounted inan agitation granulating apparatus. FIG. 7 is an explanatory viewshowing that example. The construction of the particle measurementdevice 1 is same as Embodiment, and its detailed description is omittedhere.

Here, the agitation granulating apparatus 40 is so constructed that abottom portion of a granulating vessel 41 serves as a fixed wall, anagitating blade 42 is provided therein, and a disintegrating blade 43 isprovided in a side wall of the granulating vessel 41. By tumblinggranulation with the agitating blade 42 and by disintegrationgranulation with the disintegrating blade 43, powder or granularmaterial charged into the granulating vessel 41 is granulated.

As shown in FIG. 7, in the present Embodiment 4, the particlemeasurement device 1 is provided in a lower portion of the side wall ofthe granulating vessel 41. As described above, as the granulationprocess proceed, grain size etc. are suitably measured to control thegranulation end point. In that case, conventionally in the agitationgranulating apparatus 40, it is difficult to obtain an image ofindividual powder or granular material since particles are crowdedwithin the granulating vessel 41. However, according to the particlemeasurement device 1 of the present invention, it is possible toaccurately photograph only a part of the crowded particles, since thepowder or granular material is sent into the drawing tube 3 by the highpressure gas from the gas injection nozzle 5, and the crowded particlesare dispersed and fixed on the adhesive film 6 as individuallyidentifiable particle. Namely, real-time measurement of grain size etc.is possible, and validation can be performed also in the agitationgranulating apparatus, not only in the fluidized bed granulatingapparatus.

As shown in FIG. 8, the particle measurement device 1 may be mounted inan upper portion of the granulating vessel 41. Although mountingposition of the particle measurement device 1 is not limited to theseexamples, the construction shown in FIG. 7 is more advantageous than theone of FIG. 8 in adaptation for a larger machine. In Embodiment 4, therehas been shown the example that the particle measurement device of FIG.1 is mounted onto the agitation granulating apparatus. However, as theparticle measurement device, one of FIG. 5 or 6 may be employed, ofcourse.

Next, there will be shown Embodiment 5 of the present invention, inwhich the particle measurement device of FIG. 1 is mounted in acentrifugal tumbling granulating apparatus. FIG. 9 is an explanatoryview showing this embodiment. The particle measurement device 1 has thesame construction as described in Embodiment 1, and its detaileddescription is omitted here.

In this embodiment, the centrifugal tumbling granulating apparatus 50has a rotating disk 52 provided within a granulating vessel 51, and byits rotation, granulation processing is performed on powder or granularmaterial existing on the rotating disk 52. This centrifugal tumblinggranulating apparatus 50 is a so-called centrifugal tumbling granulatingand coating apparatus which performs granulation and coating byemploying a centrifugal tumbling granulating method, and a slit 54 isopened between a side wall of a granulating vessel 51 of the apparatusand the rotating disk 52. Granulation processing is performed while slitair 44a is supplied from an air chamber 53 through the slit 54. Withinthe granulating vessel 51, liquid can be sprayed through a spray nozzle55 and powder 57 can be spread from a powder spreading device 56.

As shown in FIG. 9, in the present Embodiment 5, the particlemeasurement device 1 is mounted in a central portion of the side wall ofthe granulating vessel 51 so that the end portion of the drawing tube 3for drawing the powder or granular material is located slightly abovethe rotating disk 52. As described above, as the granulation processproceeds, grain size etc. are suitably measured to control granulationend point etc.

Conventionally in the centrifugal tumbling granulating apparatus,effective measurement has been impossible even employing a method ofphotographing in which the powder or granular material is brought intoseparated condition by air, since powder or granular material is verycrowded in a lower portion of a particle bed where the powder orgranular material representing the population exists. In other words, inthe centrifugal tumbling apparatus, adaptation for validation has beenimpossible although improvement has been desired. However, according tothe particle measurement device of the present invention, it is possibleto measure grain size etc. in real time also in the centrifugal tumblinggranulating apparatus, and validation is possible not only in thefluidized bed granulating apparatus but also in the centrifugal tumblinggranulating apparatus. Further, grain size distribution of productsbecomes sharp, and yield of the product increases.

Similarly to Embodiment 4 shown in FIG. 8, in the present Embodiment 5,the particle measurement device may be installed in an upper portion ofthe apparatus. Further, in this Embodiment 5, there has been describedthe example that the particle measurement device of FIG. 1 is mounted inthe centrifugal granulating apparatus. Of course, similarly to the caseof Embodiment 4, as the particle measurement device, one shown in FIG. 5or 6 may be employed.

Next, there will be described Embodiment 6 of the present invention, inwhich the particle measurement device 1 according to the presentinvention is provided downstream from a powder or granular materialprocessing apparatus which can perform continuous processing, andfeedback control of the powder or granular material processing apparatusis performed. FIG. 10 is an explanatory view showing an outline of itssystem configuration.

As shown in FIG. 10, the system in question has the particle measurementdevice 1 provided downstream from a particle regulator 61 connected tothe fluidized bed granulating apparatus 60. The particle measurementdevice 1 is installed in a powder or granular material transport pipe 63provided between the particle regulator 61 and a recovery apparatus 62.The particle measurement device has the same construction as describedin Embodiment 1, and its detailed description is omitted here. As theparticle regulator 61 and the recovery apparatus 62, ordinarycommercially-provided ones are employed. Further, out of the particlemeasurement devices 1 shown in FIGS. 1, 5 and 6, any one may be used, ofcourse.

In the present system, the powder or granular material processed by thefluidized bed granulating apparatus 60 is sent to the particle regulator61, and then transported to the recovery apparatus 62 through the powderor granular material transport pipe 63 by air flow caused by a blower64. The particle measurement device 1, which is provided in the middleof the powder or granular material transport pipe 63, measures grainsize etc. of the powder or granular material. In that case, between theparticle regulator 61 and the recovery apparatus 62, processing isperformed continuously, and by suitably setting processing conditionssuch as rotation speed, air pressure, and the like, particle diameter ofthe powder or granular material can be varied. Thus, when the particlemeasurement device 1 is provided downstream from the particle regulator61 as in the present system, and feedback control of the particleregulator 61 is performed based on the grain size etc. obtained in theparticle measurement device 1, it is possible to perform processingwhich keeps the particle diameter within a given range.

On the other hand, as shown in FIG. 11, the particle measurement deviceof the present invention may be provided between an extrusiongranulating apparatus 65 and a particle regulator 66. In that case, thepowder or granular material is transported through a powder or granularmaterial transport pipe 68 by negative pressure in a fluidized beddrying apparatus 67 provided downstream from the particle regulator 66or by providing a blower which is not shown. Feedback control of theextrusion granulating apparatus 65 is performed based on the grain sizeetc. obtained by the particle measurement device 1. Further, in theseexamples, feedback control may be carried out, also by providing theparticle measurement device 1 to the recovery apparatus 62 or to theparticle regulator 66.

Thus, as described above, the particle measurement device 1 of thepresent invention can be applied to feedback control of not only anapparatus which performs batch type processing such as an agitationgranulating apparatus, a fluidized bed granulating apparatus, or thelike, but also an apparatus which performs continuous processing and canvary particle diameter by setting conditions such as a particleregulator, an extrusion granulating apparatus, a crusher, or the like.Further, the particle measurement device 1 of the present invention canbe installed not only between powder or granular material processingapparatuses but also between a powder or granular material processingapparatus and a powder or granular material containing means such as acontaining vessel. Further, the particle measurement device 1 can beinstalled between powder or granular material containing means, and, forexample, the present particle measurement device may be installedbetween powder or granular containing vessels provided to respectivepowder or granular material processing apparatuses which perform batchprocessing.

Further, it goes without saying that the above-described feedbackcontrol can be applied not only for control of a preceding-stageapparatus by measuring end products, but also for control of productionprocess of intermediate product such as one which is to be tablettedafter granulation, for example. Further, the powder or granular materialprocessing apparatus to which the present particle measurement device ismounted is not limited to the above examples, and the present device canbe mounted to various apparatuses such as a crusher etc. Further, in thecase that the particle measurement device is installed between powder orgranular material processing apparatuses, combination of theseapparatuses is not limited to the above-described examples, and variousvariations are possible.

Next, there will be described experimental results of measuring grainsize etc. by using the particle measurement device of the presentinvention actually.

In this experiment, the above-described particle measurement device 1was employed in Spir-A-Flow Model 5 (trade name), a combined-typefluidized bed granulating apparatus made by Freund Industrial Co., Ltd.so as to control granulation end point. In that case, a rotor and anagitator were mounted to the above Spir-A-Flow Model 5 to performgranulation processing in the combined form of the fluidized bedgranulating method, the agitation granulating method, and thecentrifugal tumbling granulating method.

In this experiment, 3500 g of 200 M (mesh) lactose, 1500 g of cornstarch, and 250 g of HPC-L (hydroxypropyl cellulose) made by Nippon SodaCo., Ltd. were used, and granulation was performed while water wassprayed. As for the operating conditions of the apparatus, supply airtemperature was 80° C., rotation speed of the rotor was 300 rpm,rotation speed of the agitator was 450 rpm, and speed of sprayed liquidwas 100 ml/min.

Sampling by the particle measurement device 1 was performed every 15seconds, to measure an average particle diameter and grain sizedistribution. Each of these values was calculated based on the numbers.In that case, as for referential batch No. 1, spraying was stopped at 30minutes after the start of granulation and data was obtained. FIG. 12 isa graph showing time variations of average particle diameter and contentof particles with 75 μm-or-less diameter in that case, showing thataverage particle diameter increased with time and the ratio of finepowder was decreased. Table 1 shows the measurement result just beforethe stopping of spraying.

                  TABLE 1                                                         ______________________________________                                        Batch No. 1 Measurement Data by Particle Measurement Device                            Time                                                                   No. 1  (minute.second)        29.00  29.15  29.30  29.45  30.00             ______________________________________                                        Average Particle                                                                           104     106     108   109   109                                    Diameter (μm)                                                              Content of   22.6   21.7   19.8   19.6   19.1                                 Particle with 75                                                              μm-or-less                                                                 Diameter (%)                                                                ______________________________________                                    

Based on these values, control of granulation end point was performednoting two conditions: (1) 108 μm or more was repeated 3 timescontinually as the average particle diameter; and (2) 75 μm or less wasrepeated 3 times continually as the content of particles with 75μm-or-less diameter is 20% or less.

Measurement results for batches Nos. 2 and 3 are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                        Batch No. 1  Measurement Data by Particle Measurement Device                  ______________________________________                                             Time                                                                       No. 2 (minute.second) 25.30  25.45  26.00  26.15  26.30                     ______________________________________                                           Average Particle    105    107    110    111    111                           Diameter (μm)                                                              Content of  21.1   20.1   18.5   18.3   17.7                                  Particle with 75                                                              μm-or-less                                                                 Diameter (%)                                                               ______________________________________                                           Time                                                                         No. 3 (minute.second)                   27.45  28.00  28.15  28.30                                                     28.45                              ______________________________________                                           Average Particle                       101    104    107    109    109        Diameter (μm)                                                              Content of                      22.5   21.1   19.6   18.6   18.8                                                        Particle with 75                    μm-or-less                                                                 Diameter (%)                                                               ______________________________________                                    

In each batch including No. 1, there was good correlation between theaverage particle diameter and the content of particles with 75μm-or-less diameter. Accordingly, which ever of the end point controlconditions (1) and (2) was used, spraying could be stopped nearly at thesame time.

FIG. 13 shows grain size distributions for the batch Nos. 1-3 obtainedby a low tap sieve shaker. The grain size distributions of thegranulated products generally coincide with one another. Thus, it wasconfirmed that the control of the granulation end point using theparticle measurement device of the present invention was appropriate.

FIG. 14 shows comparison between granulated products obtained in thecase that control of the granulation end point is performed using theimage analysis method employing the particle measurement device 1 of thepresent invention and granulated products obtained in the case thatcontrol of the granulation end point is performed using 16 mesh sieve asin the conventional method and judging from remaining particles on thesieve. As clearly seen from FIG. 14, a standard range of desirable grainsize contains 90% of the products obtained by the particle measurementdevice of the present invention which employs the image analysis method.And it was found that a non-standard lot was not produced. Thus, incomparison with the conventional method, more precise control can beperformed by using the particle measurement device of the presentinvention employing the image analysis method.

Hereinabove, the invention made by the present inventor has beendescribed based on its embodiments. However, the present invention, ofcourse, is not limited to the above-described embodiments, and can bechanged variously without departing from the scope of the invention.

For example, in the above-described Embodiments 1-6, the control parthas been employed as the information processing means. However, meansfor processing information is not limited to this, and the data analysismay be carried out using a personal computer etc. Further, the shape ofthe drawing tube for drawing out the powder or granular material is notlimited to the one of the cylindrical shape, and a conical one may beemployed. Further, as the image pick-up means, one other than a CCDcamera, for example a still camera, may be used.

In the above-described Embodiments 1-6, the control of the granulationend point is performed by photographing particles with the particlemeasurement device. In addition to this, water content may be controlledby measuring water content in particle surfaces with an infraredmoisture meter.

In the above, the invention made by the present inventor has beendescribed for the case that it is applied to the fluidized bedgranulating apparatus as its field of utilization. However, the presentinvention is not limited to this, and may be applied to measurement ofgrain size etc. of powder or granular material in a powder or granularmaterial drying apparatus, a crusher, a coating apparatus, and the like.

The effect obtained by the representative of the inventions disclosedherein will be described as follows.

Namely, by providing the air inlet to the drawing tube of the particlemeasurement device for a powder or granular material processingapparatus, the inside of the drawing tube can be always kept clean, andit is possible to control the number of powder or granular materialadhering to the adhesive film at the time of the particle measurement.Accordingly, without being affected by pressure fluctuation within theprocessing vessel, accurate samples can be obtained always, andreliability of the measurement result is improved.

Further, since at least portion between the end surface of the drawingtube and the adhesive film is covered by the cover, and its inside ismade to be at slightly higher pressure than the inside of the processingvessel, it is possible to prevent flow out of the powder or granularmaterial through the gap between them. Accordingly, contamination of theapparatus by flow out of the powder or granular material can beprevented, and the apparatus is kept in a clean condition.

We claim:
 1. A particle measurement device for a powder or granularmaterial processing apparatus, comprising:a drawing tube for drawing outpowder or granular material, with one end portion being arranged in aninside of a container forming a part of the powder or granular materialprocessing apparatus and containing the powder or granular material tobe measured, and with the other end portion being communicated with saidone end portion and positioned outside of the container; a gas injectionnozzle for injecting high pressure gas from the inside of the containerinto the drawing tube, so as to introduce the powder or granularmaterial within the container into the drawing tube; an adhesive filmwith an adhesive surface being arranged opposed to an opening of an endsurface of said drawing tube on the side of the outside of thecontainer, so as to capture, with said adhesive surface, the powder orgranular material which has passed the drawing tube; an image pick-upmeans for photographing the powder or granular material captured by theadhesive surface of the adhesive film; an information processing meansfor processing image information of the powder or granular materialobtained by said image pick-up means; and a gas inlet communicated withthe drawing tube in a neighborhood of the end portion of the drawingtube on the outside of the container for introducing into the drawingtube through said gas inlet a gas having a higher pressure than thatexisting inside of the container.
 2. The particle measurement device fora powder or granular material processing apparatus according to claim 1,wherein:said powder or granular material processing apparatus is afluidized bed granulating apparatus.
 3. The particle measurement devicefor a powder or granular material processing apparatus according toclaim 1, wherein:said powder or granular material processing apparatusis a fluidized bed coating apparatus.
 4. The particle measurement devicefor a powder or granular material processing apparatus according toclaim 1, wherein:said powder or granular material processing apparatusis a fluidized bed drying apparatus.
 5. The particle measurement devicefor a powder or granular material processing apparatus according toclaim 1, wherein:said powder or granular material processing apparatusis an agitation granulating apparatus.
 6. The particle measurementdevice for a powder or granular material processing apparatus accordingto claim 1, wherein:said powder or granular material processingapparatus is a centrifugal tumbling granulating apparatus.
 7. Theparticle measurement device for a powder or granular material processingapparatus according to claim 1, wherein:said powder or granular materialprocessing apparatus is a centrifugal tumbling coating apparatus.
 8. Theparticle measurement device for a powder or granular material processingapparatus according to claim 1, wherein:said processing apparatusincludes a processing vessel in which said powder or granular materialcan be processed continuously, said container in which said particlemeasurement device is installed is located downstream from saidprocessing vessel and the conditions of the powder or granular materialprocessing carried out in the processing vessel are controlled based onmeasurements made by the particle measurement device.
 9. The particlemeasurement device for a powder or granular material processingapparatus according to claim 8, wherein:said container in which saidparticle measurement device is installed is a transport pipe fortransporting the material from the processing vessel.
 10. A method ofcontrolling a powder or granular material processing apparatus, usingthe particle measurement device according to claim 1, wherein:saidprocessing apparatus includes a processing vessel in which said powderor granular material is processed continuously, said particlemeasurement device is installed downstream from the processing vessel;and the conditions of the processing of the powder or granular materialin the processing vessel are controlled based on measurements made bythe particle measurement device.
 11. The method of controlling a powderor granular material processing apparatus according to claim 10,wherein:the container in which said particle measurement device isinstalled is a transport pipe for transporting the powder or granularmaterial away from the processing vessel.
 12. A particle measurementdevice for a powder or granular material processing apparatus,comprising:a drawing tube for drawing out powder or granular material,with one end portion being arranged in an inside of a container formingpart of the powder or granular material processing apparatus andcontaining the powder or granular material to be measured, and with theother end portion being communicated with said one end portion andpositioned outside of the container; a gas injection nozzle forinjecting high pressure gas from the inside of the container into thedrawing tube, so as to introduce the powder or granular material withinthe container into the drawing tube; an adhesive film with an adhesivesurface being arranged opposed to an opening of an end surface of saiddrawing tube on the side of the outside of the container, so as tocapture, with said adhesive surface, the powder or granular materialwhich has passed the drawing tube; an image pick-up means forphotographing the powder or granular material captured by the adhesivesurface of the adhesive film; an information processing means forprocessing image information of the powder or granular material obtainedby said image pick-up means; a gas communicating port communicated withsaid drawing tube in a neighborhood of the end portion of said drawingtube; and said gas communicating port being housed within a box togetherwith said adhesive film and the end portion of the drawing tube opposedto the adhesive film; said box having a gas feed port for introducing agas having a higher pressure than that existing inside of the containerinto the box through said gas feed port.
 13. A method of particlemeasurement for a powder or granular material processing apparatus usingthe particle measurement device of claim 12, comprising stepsof:injecting high pressure gas from said gas injection nozzle so as tointroduce powder or granular material inside said container into saiddrawing tube; capturing powder or granular material which has passedinto the drawing tube with the adhesive surface of said adhesive film;and photographing the powder or granular material captured by theadhesive film to obtain image information, and, based on the obtainedimage information, obtaining information on the powder or granularmaterial within the container; constantly introducing gas having ahigher pressure than that existing inside of the container into said boxthrough said gas feed port so as to keep the inside of the box at higherpressure than the inside of the container; and performing said particlemeasurement while a gas having higher pressure than that existing insideof the container is constantly introduced into the drawing tube throughsaid gas feed port.
 14. A method of particle measurement for a powder orgranular material processing apparatus, using the particle measurementdevice of claim 1, comprising steps of:injecting high pressure gas fromsaid gas injection nozzle so as to introduce powder or granular materialinside said container into said drawing tube; capturing the powder orgranular material which has passed the drawing tube with the adhesivesurface of said adhesive film; photographing the powder or granularmaterial captured by the adhesive film to obtain image information, and,based on the obtained image information, obtaining information on thepowder or granular material within the container; and performing saidparticle measurement while gas having higher pressure than the inside ofthe container is constantly introduced into said drawing tube throughsaid gas inlet.
 15. The method of particle measurement for the powder orgranular material processing apparatus according to claim 14,wherein:said powder or granular material processing apparatus is acentrifugal tumbling granulating apparatus.
 16. The method of particlemeasurement for the powder or granular material processing apparatusaccording to claim 14, wherein:said powder or granular materialprocessing apparatus is a centrifugal tumbling coating apparatus. 17.The method of particle measurement for the powder or granular materialprocessing apparatus according to claim 14, wherein:said powder orgranular material processing apparatus is a fluidized bed granulatingapparatus.
 18. The method of particle measurement for the powder orgranular material processing apparatus according to claim 14,wherein:said powder or granular material processing apparatus is afluidized bed coating apparatus.
 19. The method of particle measurementfor the powder or granular material processing apparatus according toclaim 14, wherein:said powder or granular material processing apparatusis a fluidized bed drying apparatus.
 20. The method of particlemeasurement for the powder or granular material processing apparatusaccording to claim 14, wherein:said powder or granular materialprocessing apparatus is an agitation granulating apparatus.